All members of the kingdom Animalia need oxygen to make energy. Oxygen is compulsory. Without oxygen, we die. But as you know, the byproduct of the process that keeps us all alive, cellular respiration, is carbon dioxide, or CO2, and it doesn’t do our bodies a bit of good, so

Let me introduce you to one of the bravest pioneers in the history of life on planet Earth. An organism that blazed the trail for every single vertebrate that lives on land today — and many that don’t. It’s one of your most important ancestors. Meet…well, it doesn’t have a

Maybe you’ve noticed that every time we talk about a new system, we highlight its importance by saying how you’d die without it. Like, without your muscular and skeletal systems you’d collapse into an inert bag of goo. Or how if we magically removed your respiratory or circulatory system, you’d

Don’t take this the wrong way, but you’re pretty replaceable. When it comes to your body, science has figured out how to hack, synthesize, or replace a surprising amount of its parts and processes. We have implants to keep heart beats steady, and steel rods to mimic bones. We’ve got

You know, we’ve been talking about a lot of serious stuff here lately. Heart failure. Respiratory gas exchange. People with holes in their stomachs. Nachos. Some might say I’ve even been flaunting my ability to eat, digest, and enjoy a plate of chips and melted cheese. And I wouldn’t blame

Here’s a couple of words you might find useful in the study of human metabolism. They also happen to be two words that I enjoy in general. Brunch. Buffet. I’d throw in “all you can eat,” but that’s kind of implied, and then it would be six words, unless you

I’ve invited you all here today because I wanted to talk to you about some ugly stereotypes that are going around. I’ve been hearing a lot of unfair, unseemly, and unscientific generalizations being made lately. And they mostly have to do with sex. And your hormones. People have a nasty

We all have our reasons for eating nachos at 3 in the afternoon. I happen to have my own. And don’t ask — it’s personal. But more generally, we all eat any kind of food to accomplish two simple things: to obtain the energy we need to stay alive and

In the summer of 1822, a French-Canadian fur-trapper named Alexis St. Martin was going about his business near Lake Michigan, when he was shot by a hunter, right in the stomach. The wound was severe, and everyone expected St. Martin to die that night. But…he didn’t. A local army doctor